Protractor



April 30 1945. M c. sMlTiln 2,399,579

l PROTRACTOR Y Filed Feb. 18. 1944 Patented Apr. 30, 1946 UNITED STATES PATENT OFFICE PRoTRAo'ron Neil C. Smith, Minneapolis, Minn. Application February 1s, 1944, serial No. 522,941

(ci. sa-iozi' 4 Claims.

Mypresent invention relates to improvements in protractors. l

More particularly, this invention is in thenature. of an. improvement', on or refinement of the protractor disclosed and claimed in United States Letters Patent No. 2,316,189, issued April 13, 1943, to Timothy A. Schaefer, inventor, and assigned -to the Industrial Engineering Co. Inc.

The principal object of this invention is the provision of novel means for locking the movable elements of the protractor where adjusted.

To theabove end, the invention consists of the novel devices and combination of devices hereinafter described and defined in the claims.

In the accompanying drawing, which illustrates the invention, like characters indicate like parts throughout theseveralviews.

Referring to the drawing:

Fig. 1 is a plan view of a protractor having one form of the invention embodied therein;

Fig. 2 isa fragmentary detail view principally in section taken on thefline 2-2 of Fig. 1, on an enlarged scale;

Fig. 3 is a view principally in section taken on the line 3--3 ofjFig. 1, on an enlarged scale;

Fig. 4 is a fragmentary detail view partly in plan and partly in section taken on the line 4-4 oi Fig. 3;

Fig. 5 is a fragmentary plan view of a protractor having another form of the invention embodied therein;

Fig. 6 is a view principally in section taken on the line 6-6 of Fig. 5, on an enlarged scale;

Fig. 7 is a fragmentary detail view partly in plan and partly in section taken on the line I--l of Fig. 6; and

Fig. 8 is a fragmentary Vdetail view partly in elevation and partly in section taken on the line B- of Fig. 6.

Referring rst to the invention shown in Figs. 1 to 4, inclusive, the numeral 9 indicates the body of a protractor and which body is in the form of a blade having parallel longitudinal edges. One end portion of the body member 9 is enlarged to afford a head III. One of the longitudinal edges of the body 9 affords a long straight-edge I I that extends the full length thereof. The end of the body 9 at the head III affords a short straight-edge I2 which extends at right angles to the first noted straight-edge. A scale I3 graduated in inches and fractions thereof is marked on the body member 9 at the long straight-edge II.

A turret I4 is attached to the head III to turn about a tubular pivot I5 in a plane parallel to the plane of the body 9. This pivot I5 is internally screwL-threaded and has on one end an external-annular flange It countersunk in the head I9 at its back and rigidly secured thereto. The .pivot I5 is located exactly the same distance from the two straight-edges II and i 2 and has in its outer end two diametrically opposite keyways I'I.

A large thinwasher I8 on the pivot I5 is interposed between the head I0 and the turret I4. In the face of the turret I4 is a depression I9 that is concentric with the pivot I5. A relatively thin washer 29 on the pivot I5 rests on the bottom of the depression I9 and a relatively thick washer 2I rests on the washer 20 and extends outwardly of the pivot I5. Keys 22 on the washer 2I extend into the keyways I'I and hold said washer from turning on the pivot I5, but with freedom for relative axial movement. A screw 23 for clamping the turret I4 onto the washer I8 has a large head that engages the washer 2|. By tightening the screw 23 the turret I4 may be frictionally held from turning relative to the body 9 so as to remain where adjusted. Obviously, the pivot I5 acts as a fixed nut for the screw 23.

More than one-half of the turret I4 is on the arc of a circle and concentric with this circle is an annular scale 24 having two diametrically opposite zero points 25 and 26, Each quadrant of the scale 24 is divided into ninety degrees reading in opposite directions from each zero point. The degree reading at the zero point 25 is the required angle and the degree reading at the zero point 26 is the component angle.

Mounted on the turret I4 is an adjustable Vernier plate 21 on which appears a vernier scale 28 for co-operation with the scale 24.

A long thin arm 29 is mounted in the passageway in the turret I4 for endwise sliding movement in a plane parallel to the plane of the body 9. One end of the arm 29 extends at a right angle to the longitudinal edges thereof and the other end of said arm is on an angle of forty-live degrees (45). A scale 30 on the arm 29 is graduated into inches and fractions thereof. The arm 29 is frictionally held Where endwise adjusted relative to the turret III by ya spring member 3|.

To simultaneously lock the turret I4 relative to the body 9 and the arm 29 relative to the turret I4, I provide a, thumbscrew 32 having a knurled head for locking the turret I4 to the body member 9 and an elongated washer-like member 33 for locking the arm 29 relative to the turret I4. The screw 32 has threaded engagement with the turret I4 and impinges the body 9 and the member 33 has an elongated hole near one end through which the screw 32 extends. The member 33 at its short end rests 0n the turret I4 and on the long end of said member is a laterally projecting or depending finger 34 that extends through a hole 35 in the turret I4 and impinges the arm 29. A large annular boss 36 on the under side of the head of the screw bears against the member 33 and holds said head spaced from the mem* ber 33. The length of the finger 34 is such as to hold the member 33 out of contact, except at its short end, with the turret I4 and in a slightly inclined position, see Fig. 3.

Referring now to the invention shown in Figs. 5 to 8, inclusive, wherein parts that correspond to like parts in Figs. 1 to 4, inclusive, are given the same reference numerals followed by a prime (')1 In the structure shown in Figs. 5 to 8,; inclusive, a single thumb-screw 31 having a knurled head and a co-operating-washer perform the same functions as the two screws 2'3 and '32,"v and the washer-like member 33 shown in Figs, 1 tov 4, inclusive-f The screw' 3T liasthreacled engagef ment with the tubular pivot "|754" and loosely Vextends through the hole Vin `the washer 38. Said washer 38 is interposed' between the head ofthe screw 3l and the washer ZI. A large boss 39 on the Linder side of the'head of vsaidv screw bears on thewasher 38. Formed with' the Washer 38 are two diametrically opposite and laterally projecting or depending lingers 40I which extend through the holes 4I in the turret I4y and impinge the head I0. Also formed with the Washer'38, midway between the ngers 40, is an extension 42 having on itsv outer end a 1atera1ly"projecting linger 43. This linger 43 extends through "a hole 44 in the turret I4' and impinges the arm 29.

The initial tightening of the srew 31 will frictionally clamp the turret I4' 'and hold the same where adjusted relative to the head [0. Further tightening, oftheserew 3'!l will press'the iingers4 40 into the headl II'I andtheling'erI 43 onto the arm 29- and thereby positively'holdtheturret I4' and the arm 2 3 Where adjusted.

What'I claim is:

1. rI-he combination with a body member, of a.

turret on the body member, an arm mounted on the turret for endwise sliding movement, a member having a depending nger impinglng the arm, and a screw operable on the member to simultaneously hold the turret against pivotal movement relative tothe body member and to hold the arm against endwise sliding movement relative to the turret.

2. The combination with a body member, of

aturret'on the body member, an' arm mounted on the turret for endwise sliding movement, a member, one end of which engages the turret and having on its other end a depending finger extending through a hole in the turret and impinging the arm, and a screw extending through an aperture in the member and operable on the member to simultaneously hold the turret against pivotal movementrelative to the body member and to hold the arm against endwise sliding movement relative t9 the, turret 3,."Ihe combination with a body member, of a turret, means including a, headed sorew fr pivotally eonnecting the turret to the body member, anarmA mounted on' the 'turret for Ver'idwise slidins mevement'arida Washeren th srgw hav* ing depending fingers impiriging the"body member andthe arm,l 'saidscrewfbein'g operable on the washerto clamp the'ngers Aonto the 'body member and the arm.

4. The `combination with a body member, of a turret; means includinga"headedscrew for pivotally connecting the turret tothe Kbody member andffrictionally. holding the samewhere adjusted, an'arm mounted onv the turretio'r'endwise slidingY movement, and a washeron the screw having a pair of diametrically opposite depending lingers extending throughhole'sfinthe turr'=,t"'and impinging the body member; saidfwasher also having a radial extension betweenis'aid ngers; said extension havingon'its outer end a depending nn'- ger extending]through a lioleimthe turret and impingingthe arm, said 'screw being 4'operable on the washer to clamp the fingers ontofthe' body member and thea'rm;v

' i NEIL C. SMITH. 

